I'm part of a college club and our project involves casting and machining a part. We have solidworks models for the finished product. However, we need to create a raw casting that will be machined into the final part. We are planning on using cores for some areas of the casting and I want to use the finished models to make models of the cores. If that makes sense? I am having trouble with doing that. Any guidance would be much appreciated. I have attached the model.

The classic way to do this is to put your part in an assembly, make a simple part that is slightly larger than your core (typically by an extrude or revolve), then use the Cavity feature to subtract the part from the core base, leaving your core. (You need to be editing the core part in the assembly.)

It is usually considered good practice to scale your original part to allow for the shrinkage.

You will need to have a configuration of your part that shows the original as-cast part, without the later machining.

You can also do something similar in a mult-body part, using the Combine feature instead of a Cavity, but that doesn't make as much sense to me as doing it in the mold assembly.